The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Solid state memory devices, such as flash memory devices, often have a limited lifespan. In particular, memory cells within a solid state memory device are erased prior to being written with new data. But those memory cells can only be erased a certain number of times before data retrieval from those memory cells starts to become unreliable. Various methods are employed to make flash memory devices last longer, such as wear leveling. Wear leveling attempts to write new data to memory cells that have had fewer previous writes than other cells. Also, stable data (data that is stored for a relatively long time and is infrequently changed) may be moved to a new location to free up the relatively under-written memory cells that the stable data previously occupied. This way, the memory cells in the device can be aged at approximately the same rate, thereby extending the life of the solid state memory device. But these operations become more difficult as the solid state device reaches a relatively full state.